Chaudhary Aslam, a senior police official, confirmed that Sheikh had been killed besides two others in the bomb attack.

At least three people, including an ex-chief security officer of President Asif Ali Zardari, were killed and about 12 others injured today when a powerful blast targeted a bullet-proof vehicle in a congested area here.

Bilal Sheikh, chief security officer of President Asif Zardari and a prominent leader of the Pakistan Peoples Party (PPP) was killed when the bomb ripped through his double cabin car in Gurumandir area, one of the city's busiest location.

Chaudhary Aslam, a senior police official, confirmed that Sheikh had been killed besides two others in the bomb attack.

Police said that about 12 people were injured in the bombing.

Aslam said apparently the remote controlled bomb was planted in the double cabin car and was detonated when the car was at Gurumandir where it stopped for a while.

"It was a remote controlled bomb and it caused lot of damage," another police official of the area said.

Sheikh, a die-hard leader of the PPP was party president of the central district in Karachi and had also worked as chief security officer of the President in the past.

"He had received several threats and a cracker bomb attack was also carried out against him in Nazimabad two months back. He was transferred from the Presidency to Karachi," an officer said.

Television channels gave conflicting reports that the bomb was planted on the roadside and was detonated when the car passed it.

An eyewitness said that besides the those in the car several other bystanders were injured by the blast.

Some vehicles which were close were also damaged, the eyewitness said.

"It was a powerful explosion and it caused plenty of damage and also spread panic and fear in the area with shops closing down immediately afterwards," a rescue official said.